When it's not raining, speak with him and select "Is it a cat?" then head outside and speak with the cat.
Quest 13: The player will need to speak with the man in Floodplain.The next day, return and select "Apologize to her" to finish the quest. Speak with her during a dry day (no rain) and select the "Do you need help speaking?" and "Give her lessons" dialogue. Players can speak to the girl on the high school roof to begin this quest. Quest 12: The player will need to have their Understanding and Courage social link both at Rank 3.Once it's done, take the model back to the guy to complete the quest. He will give the player a model set that the player can build in their room for 4 days. Speak with him during cloudy or sunny weather. Quest 11: Players can begin this quest by speaking with a Man by the Hobby Shop in the North Shopping District.Give this sticker to the boy the next day to complete the quest. The next day, speak with the boy again then return in the evening to speak with Nanako and choose "Ask Nanako About Stickers" then "Thank You". Give him a Prize Sticker that can be obtained by ordering it from Tanaka's TV Shopping program. Quest 10: Players can begin this quest by speaking with the boy near the signs in Floodplain.Give it the Steak Skewer to finish the quest. It can be purchased in the North Shopping District.
Come back the next day and head to Floodplain with a Steak Skewer. After speaking with the dog, return to the North Shopping District another day and select "Talk to it gently." The next day, go to Floodplain and speak with the dog and select the same dialogue option. This is another quest that needs to be done throughout multiple days.
After speaking with the girl, return the next day and select the first dialogue option she offers. This quest can only be done in parts, once per day.